1. Field of the Invention
This invention is related to computer language compilers and particularly to program include statement processing.
2. Description of the Related Art
Computer language compilers are well known in the art. Basically, a compiler is a computer program that translates a computer source program into an executable program, or object program. The input to the compiler is source code, which is written in a source language such as C++. The output from the compiler is object code, which is itself executable machine code or is suitable for processing to produce executable machine code. Note that in general, the term "compiler" applies to programs written in high-level languages, and the terms "translator" and "assembler" apply to low-level computer languages or assembly languages. In this document, the term "compiler" is used to mean any and all of these things.
A source program may contain one or more preprocessor directives known as include directives or include statements. Each include statement directs the compiler preprocessor to replace the statement with the contents of a specified file, known as an include file. An include file is a source file that is used by including it (i.e., inserting it inline) in a program being compiled during the compiler preprocessing phase. Normally, include files contain common data format definitions, common constant definitions, common executable macros, or common subroutines.
Include files normally reside in libraries contained in specified subdirectories. An include statement may explicitly specify the library containing an include file by specifying a drive and path location. Otherwise, include file libraries are specified by compiler options that are known as include options. An include option is a compiler option (i.e., an optional compiler meta-statement) for specifying which program library or libraries to search for files specified in include statements. Include options function in a manner similar to PATH statements in DOS and its derivatives to specify a search path for locating files (in this case, include files).
Conventionally, when writing source code with include statements, the library containing the include files must reside on either a local drive or a connected network drive; "connected network" here means either a local area network (LAN) or other network in which LAN server disk drives or other disk drives can be accessed as if they were locally connected to each client system on the LAN. In an OS/2.RTM., Window.RTM., or DOS environment, the LAN server disk drives are referred to by a drive letter such as W: or Z:. In a UNIX.RTM.-based system, access to remote files is accomplished via a network file system (NFS) and is limited to disk drives attached to systems comprising the LAN. In both the above cases, a language compiler accesses the accessible disks as if they were locally attached.
As a result of this local access requirement for the include file libraries, two sets of expenses are incurred. First, software producers pay media and distribution costs for the (sometimes rather substantial) amounts of data written on disks or CD-ROMs that are used for product distribution. Second, users have to allocate substantial amounts of space on their personal computers to store the source libraries distributed with compilers and product application program interfaces (APIs). With the introduction of thin clients (cost-reduced computers having small amounts of memory and disk space that rely on a network to store most of their data), the situation becomes even more problematic.
Other reasons for dissatisfaction with the existing art relate to the practice of team software development. During development of software, programmers within a development team are conventionally given access to the same local area network (LAN) so that they can easily share their data. This practice is based on the paradigm ascribing most or all of the programmers in a team to a single company developing code.
With the widespread acceptance of the Internet and the emergence of virtual enterprises, this static team paradigm is being replaced with that of a dynamic, widely dispersed team of programmers, cooperating on a development project across vast distances, time zones, continents, etc., making it impossible to place all of the software developers on a single LAN. It is often necessary for a team of programmers to be able to access a common set of source libraries that, because of the distances involved, cannot be made available on any single LAN as a single instance.
A number of products (e.g., IBM TeamConnection) exist for software version management and group development, however, they either provide programmers with access to shared data within a LAN or replicate data among LANs or single nodes. Some way to access common source libraries is what is required.